build: downgrade maven-sources-plugin from 3.3.0 to 3.2.1

The new version of the plugin caused build failure because of duplicate configurations.

pom.xml

@@ -1,13 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <packaging>pom</packaging>
 
   <parent>
     <groupId>org.camunda.community</groupId>
     <artifactId>community-hub-release-parent</artifactId>
     <version>1.4.3</version>
-    <relativePath />
+    <relativePath/>
   </parent>
 
   <groupId>io.zeebe.zeeqs</groupId>
@@ -314,6 +316,10 @@
           <artifactId>nexus-staging-maven-plugin</artifactId>
           <version>1.6.13</version>
         </plugin>
+        <plugin>
+          <artifactId>maven-source-plugin</artifactId>
+          <version>3.2.1</version>
+        </plugin>
       </plugins>
     </pluginManagement>
   </build>